The invention herein described relates to devices for repairing injuries in tubeless tires and, in particular, to the repair of tubeless tires having belts under the tread thereof constructed of stiff materials such as steel.
Tubeless tires which have been punctured usually are repaired by inserting into the injury in the tire a flexible plug having a diameter larger than the diameter of the injury. One such plug is shown in U.S. Pat. No. 2,966,189, issued to Chambers et al.
An apparatus for inserting such plugs into early tubeless tires is disclosed in U.S. Pat. No. 3,714,851, issued to Orser. A device of the type disclosed in Orser is more convenient than prior plug inserters because a user merely hooks the plug into the eye of a needle, stretches the plug along the sides of the needle using a clamping apparatus built into the device, inserts the needle carrying the plug into the injury of the tire, releases the clamping mechanism and withdraws the needle. Problems have arisen, however, with prior art devices of this general type which are used to repair tubeless tires having stiff belts such as steel underneath the tread. As the needle passes through the injury in the belt, the stretched plug tends to be sheared off by the steel belt at the exposed shoulders of the plug where it emerges from the eyelet of the needle. The initial response to this problem appears to have been to form the plug of tougher material to withstand the shearing edge of the steel belts. A disadvantage of this approach has been that a gain in toughness has been accompanied by a loss in flexibility in these new plugs which do not seal as well as more vulnerable plugs.
The prior art indicates that attempts have been made in connection with other types of plug insertion devices to shield and guide a plug through an injury in a tire. Examples of such prior art include U.S. Pat. No. 4,009,624, U.S. Pat. No. 611,972, and U.S. Pat. No. 567,402. However, tools of the older prior art disclosures appear to be less convenient to manipulate and in some instances more than one tool is required to accomplish the plugging function. Furthermore, it appears that the rigidly shaped protective sleeves for plug inserters of the prior art require that a small injury be enlarged to the diameter of the sleeve in order that the sleeve may be passed through the puncture. Although this may have been a simple matter when repairing early tubeless tires, the mesh of present day steel belts is very stiff and resistant to attempts to enlarge injuries through the belt.